Pneumatic hand-hammer.



PATENTED MAR. 22., 1904.

, IA. T. F. NEHLS. PNEUMATIC HAND HAMMER.

APPLIoATIoN FILED APR, 2a. 1902.

N0 MODEL.

Unirse Str-Arias Patented March 22, 1904..

Artnr @tripa PNEUIVIATFC HAND-HAMMER.

SPECIFICATION forming part of Letters Patent No. 755,381, dated March 22, 1904..

Application tiled April Z3, 1902. Serial No. 104,263. (No model.)

T0 all whom, t may concern:

Be it known that I, AGUsT THEoDoR FRIED- RICH NnHLs, a subject of the King of Prussia, German Emperor, residing at Siidende, near Berlin, in the Kingdom of Prussia, Germany, have invented certain new and useful Improvements in Pneumatic Hand-Hammers, of which the following is a specification, such as will enable others skilled in the art to which it appertains to make and use the same.

rIhe object of my invention is to provide a pneumatic hand-hammer of an extremely simple and cheap form of construction, consisting of but few parts and not liable to accidental disarrangement or accident, in which the moving' -portions of the valve are plungers actuated in one direction by the piston-plunger and in the other by the compressed air.

To such ends my invention consists, in substance, of a casing having' a cylindrical hollow, a plunger-piston reciprocating in the casing, a reciprocating tool-stock passing through one end of the casing adapted to be forced outward by the impact therewith of the plunger-piston, a hollow valve-piston adapted to have a limited reciprocative movement located at either end of the cylinder adapted to be reciprocated toward the end of the cylinder by the impact therewith of the pistonplunger and in the other direction by the air-pressure when the piston-plunger has reached the other end of the cylinder, an annular air-groove formed on the-periphery of each of the valve-` pistons, a plurality of passages or ports formed in and through. the peripheral wall of the pistons, an end plate closing either endl of the casing, a hollow handle-piece adapted to be connected with a suitable air-pressure-supply hose or pipe, an inlet or throttle valve, means for actuating the throttle-valve, and air inlet and outlet passages formed in the walls of the casing, by which upon reciprocating of the valves first one side and then the other are alternately brought into communication with the air-pressure supply and with the atmosphere, although it is not to be understood that the device is limited to a device comprising at once all the devices and parts or the particular construction, combination, and arrangement of parts mentioned, as my invention consists in the particular arrangement of certain devices and parts and the particular construction and arrangement of certain devices and parts, all as hereinafter more particularl y set forth in the description and pointed out in the claims.

My said invention is fully shown and described in the following specification, of which the accompanying drawings form a part, wherein similar letters of reference designate like or equivalent parts wherever found throughout the several views, and inwhich- Figure l is a side view of my improved form of pneumatic hand-hammer in central longitudinal section on the line 2 2 of Fig. 5, the plunger-piston being shown in the center and moving toward the right in the position assumed by it when about to strike the working blow. Fig. 2 is a similar view thereof, taken in section on the line 3 3; and Fig. 3, a similar view taken in section on the line 4 A of suoli Fig; 4. Fig. 4 is an end view of Fig. 1 looking toward the left, taken on the line 5 5 of Fig. l, the handle-cap portion being wholly removed; and Fig. 5 is a like view taken in cross-section on the line 6 6 of such Fig. l. Figs. 6 and 7 are views similar to Figs. l and 2, respectively, showing the position of the piston-plunger and valve-pistons at the moment when the plunger-piston is about to start upon its reverse reciprocative movement immediately after having struck its working blow. Y

Referring to the drawings, the referenceletter A designates a cylindrical casing, to one end of which is secured the handle-cap B and to the other the nose-cap C, through which reciprocates the shaft a", of the reciprocating tool, a fianged bushing c', of suitable antifriction metal, being interposed between the stem of the tool :c and the nose-cap, as shown, upon the inner end of which reciprocates back and forth the outer piston-valve g, a similar piston-valve c being located in the other end of the cylinder and the travel of each being limited by the length of the recess g or n, which is in each case of slightly-larger diameter than the cylinder-bore, a plate r1 performing the function for the valve c performed for the valve g by the iiange of the bushing c', such plate o" being IOO provided on the outer face with a groove s in free communication at one end with a passage t and at the other with the valve-chamber at the rear of the valve c, as shown in Figs. 3 and 4, and also with perforations in registryv with the inlet-passage and the exhaust-passage L, as shown in Figs. l and 6, while the flange of the bushing a' is provided with a groove m and passage fw, similar to the like groove and passage s and t.

rlhe piston-valve e is provided with a plurality of holes c, formed in and through the peripheral wall thereof, so as to communicate with the central cavity thereof, which is of such size as to receive the end of the plungerpiston` f, and the like valve r/ is provided with a similar central cavity and similar holes d, and upon the base of each of such piston-valves is formed an annular groove, (designated in the case ofl the valve e by u and of g by n.) The plate or flange vf of the bushing of the nosepiece upon the central hollow spindlevof, which the valve g reciprocates is provided with a groove and two perforations, as shown in Figs. 2 and 7 by which the rear face of the valve g isat all times in free communication with .-the

passage 715, formed in the wall of the casing,v

the other end of ,which passage /r is provided with a port opened and closed by the reciprocation of the valve e, a like passage o on the other side of the casing being in communication with a passage p, similar to thepassage Z, the port of which passage 0 is opened and closed by the reciprocation of the valve-piston g.

Formed in the wall of the casing is an airentrance passage b, provided with a port at either end adapted to be opened and closed by the reciprocation of the piston-valve at that end, entrance being had by way of the peripheral perforations in the valve-piston, such passage being in communication with the passage in the hollow handle, to the end of which is secured the air-pressure-supply hose, (not shown,) in which passage a is located the valve c, manipulated by the pressure of the operators hand upon the valve-lever in the well-known manner, and formed in the wall of the casing on the opposite side and in free communication with the atmosphere is the cX- haust air-passage 7L, provided at either end with two ports /L and c, the port /t being adapted to be brought into andout of communication with the central portion of the cylinder by way of the perforations c or (Z, as the case may be, upon the reciprocation of the valve andv the port 'u' in like manner being by such reciprocation brought into and out of communication in the one case with the peripheral groove u of the valve-piston e and in the other with the like groove a of the valve-piston y, which grooves when the valves are in such position as to bring them into registry with ythe port are in the case of the valve e in registry with the passage t in communi- Acation with the passages and in the case of the other valve with the passage w in communication with the passage m in the end plate.

The operation of the device isas follows: The plunger-piston f being at the handle end of the cylinder, if now the valve c be opened by pressure exerted upon the -lever thereof the compressed air will pass to the cylinder by way of the passages a and Z2' and holes c in the peripheral wall of the valve, and such pressure will force the piston-plunger f to the nose end of the cylinder in lthe direction of the arrow marked on such plunger in Figs. l, 2, and 3, the exhaust-air in front of such piston-plunger f escaping freely into the atmosphere by way of the perforations CZ of the valve g and exhaustpassage L, and during this movement the groove a is in registry with the port leading to such passage /L and with the passages t and s, as shown in Fig. 3. At the same instant that the plunger f delivers its working blow upon the inner end of the tool -shank a' it also strikes against the valve-piston g and forces the same back against the nose-piece of the casing into the position shown in Figs. 6 and 7, thepblow upon theA of the port and perforations Z of such valve and such cylinder at the same time, by way of some of such perforations (Z, brought into communicationwith the passage p in communication with the rear or outer face of the valvepiston e by way of the channel or passage p, which is thus by thepressure of the air forced forward into the position shown in Figs. 6 and 7, so as to close the air-inlet port of the passageb and open the exhaust-port u at the handle end, as shown in Fig. 6, and to at the same time close the port of the passage r, leading to the passage c, passages 0 and j) of reversed position performing similar functions for the other valve on the forward movement.

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The handle B and nose-piece C are usually removably secured upon the `ends of the cylinder A by meansof set-screws je/ and y, and by having' cylinders A of different lengths one tool may be used for many different purposes.

Having now particularly described my said invention, what l claim, and desire to secure by Letters Patent, is-

l. In a pneumatic'hammer a removable handle-piece, a removable nose-piece, means for detachably securing same to cylinders of different lengths, a plunger-piston, and a removable valve-piston at either end of the cylinder y removable therefrom when the end pieces are removed actuated in one direction by the airpressure and in the other by the plunger-piston, substantially as shown and described.

2. In a pneumatichammer, a cylinder, a plurality of air-passages form ed longitudinally of the cylinder in the wall thereof, a valve-piston located in the cylinder at either end capable of a limited reciprocative movement therein adapted to open and close the ports of the air-passages so as to bring both sides of such valve-pistons alternately into communication with the air-pressure passage and the exhaustpassage, and a plunger -piston rcciprocated in thecylinder by the air-pressure adapted to force the valve-pistons to the end of the cylinder upon impact therewith,

substantially as shown and described.

3. In apneumatic hammer, a cylinder, a plurality of air-passages formed longitudinally of the cylinder in the wall thereof, a valve-piston located in the cylinder at either end capable of a limited reciprocative movement therein adapted to open and close the ports ofthe airpassages so as to bring both sid es of such valvepistons alternately into communication with the air-pressure passage and the exhaust-passage, a plunger-piston reciprocated in the cylinder by the air-pressure adapted to force the valve-pistons to the end of the cylinder upon impact therewith, and means for causing an aircushion to be formed behind the valve-piston to receive the first impacting force of the plunger-piston and for releasing the air so compressed behind such valve-piston during the latter portion of the outward move of such piston.

4.-. In a pneumatic hammer, a cylinder, a plunger-piston, an enlarged recess formed in each end of the cylinder, a valve-piston reciprocating in cach of such recesses having an inwardly-faced central recess provided with perforations in the peripheral wall and with an annular vgroove upon the periphery of the base, an air-entrance `passage provided with an air-port at either end extending longitudinally of the casing, a like air-exhaust passage at either end with two ports one adapted to be put into and out of registry the one with the perforations and the other with the peripheral groove of the adjacent valve, such exhaust-passage being in free communication with the atmosphere and extending longitudinally of the casing, a valve-actuating airpassage in free communication at one end with the chamber between the outer face of the valve and the cylinder end and provided at the other with a port adapted to be brought into and out of communication with the cylinder upon the reciprocation of the valve adjacent to the port, a similar passage reversely located so as to perform a like function for the other valve, and an exhaust air-passage for each of the valve-pistons in communication at one end with the chamber between the outer face of the valve-piston and the casing end and provided at the other with a port adapted to be brought into and out of communication with the peripheral groove of the valvepiston as the same is reciprocated, substantially as shown and described.

5.' In a pneumatic hammer, a cylinder, a plunger-piston, an enlarged recess formed in each end of the cylinder, a valve-piston reciprocating in each of such recesses having an in- .wardly-faced central recess provided with perforations in the peripheral wall and with an annular groove upon the periphery of the base, an air-entrance passage provided with an airport at either end extending longitudinally of the casing, a like air-exhaust passage provided at either end with two ports one adapted to be put into and out of registry the one with the perforations and the other with the peripheral groove of the adjacent valve, such exhaustpassage being in free communication with the atmosphere and extending longitudinally of the casing, a valve-actuating' air-passage in free communication at one end with the chamber between the outer face of the valve and the cylinder end and provided at the other with a port adapted to be brought into and out of communication with the cylinder upon the reciprocation of the valve adjacent to the port, a similar passage reversely located so as to perform a like function for the other valve, and an exhaust air-passage for each of the valve-pistons in communication at one end with the chamber between the outer face of the valve-piston and the cylinder end and provided at the other with a port adapted to be in communication with the peripheral groove of the valve-piston only during the latter portion of the outward movement of such piston, substantially as shown and described.

6. In a pneumatic hammer, a cylinder, a plunger-piston, an enlarged recess formed in each end of the cylinder, a valve-piston reciprocating' in each of such recesses having an inwardly-faced central recess provided with perforations in the peripheral wall and with an annular groove upon the periphery of the base, an air-entrance passage provided with an airport at either end extending longitudinally of the casing, a like air-exhaust passage provided at either end with two ports one adapted to be put into and out of registry the one with the perforations and the other with the peripheral groove of the adjacent valve, such exhaustpassage being' in free communication with the atmosphere and extending longitudinally of the casing, a valve-actuating air-passage in free communication at one end with the chamber between the outer face of the valve and the cylinder end and provided at thc other with a port adapted to be brought into and out of communication with the cylinder upon the reciprocation of the valve adjacent to the port, a similar passage reversely located so as to perform a like function for the other valve,

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and an exhaust air-passage for eaeh of the communication With the port of the air-eX- IO Valve-pistons 1n communication at one end hanst passage, substantially as shown and de- 4 with the chamber between the outer face of scribed.

the valve-piston and the cylinder end and In Witness whereof I have hereunto set my provided at the other with a port adapted to hand in presence of tWo Witnesses.

be in communication with the peripheral lAUGUST THEODOR FRIEDRICH NEHLS. groove of the valve-'piston only during the Witnesses: latter portion of the outward movement of E. H. L. MUMMENHOFF,

suoli piston, such groove at the same time in OTTO WV. HELLMRICH. 

